The present invention relates to a capsule for the preparation of a coffee extract from coffee contained in the capsule by hot water injected under pressure in the capsule using a water injection device having perforating blades. The invention also relates to a system of capsule comprising the capsule of the invention associated to a water injection device in a beverage production device.
The background of the present invention is the field of capsules which contain beverage or other comestible ingredients. By means of an interaction of these ingredients with a liquid, a beverage such as coffee, tea or other comestibles, such as for example soup, can be produced. The interaction can be based on the principle of extraction of a beverage-forming substance, the mixing or the dissolution, in presence of a liquid diluent such as water.
The capsule of the invention is more particularly adapted to contain ground coffee in order to produce a coffee beverage by injecting hot water under pressure into the capsule and obtaining a coffee beverage from the capsule.
Systems and methods for obtaining fluid comestibles from substances containing capsules are for example known from European patent application EP 512 470 A. Therefore, the capsules are closed by walls, preferably liquid impermeable walls including an inlet wall which is pierced only during use, for injection of water, for example, when the capsule is introduced in the device.
An improvement in these systems and methods consists in providing an injection device comprising a series of blades separated from the central injection conduit as described in European patent EP 12 99 022 B1. A better flow distribution is obtained as compared to a central perforation obtained by a single injection needle. Such device works properly with a capsule body made of thin aluminum because that material tends to perforate easily due to its mechanical properties. Furthermore, the perforations can be well dimensionally and geometrically defined and therefore they provide a good flow distribution across the bed of ingredients in the capsule. However, the known embodiments suffer the disadvantage that certain capsules made of more elastic materials such as polymers can be difficult to pierce in a repeated manner and the resulting perforations are not so well dimensionally and geometrically defined. This is especially true for capsules comprising plastic walls or biodegradable polymers, as the material can be relatively difficult to pierce and the piercing members of the device may become blunt relatively rapidly. Therefore, new capsules can no longer be pierced correctly, i.e., they are pierced partially or insufficiently thereby providing poor flow distribution of liquid in the capsule which affects the quality of extraction and the qualities of the liquid food that is produced. The beverage preparation device may also have to be returned to a service or maintenance station for repairing or replacing the piercing members which have been damaged.
The present invention aims at solving this problem by providing a capsule which is more easy perforable for ensuring a good quality of extraction and which does not damage the injection devices of the existing art or of existing beverage preparation devices.
WO2010/041179 relates to a capsule for preparing a beverage with an upper wall comprising on its internal surface a weakening zone adapted to be displaced when an external element exerts a force thereon.
Despite the foregoing, further improvements are needed and these are now provided by the present invention.